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I AIR PUMP. I N0.,508,495. v Patented Nov. 14, 1893.

UNITED STAT S PATENT Fries.-

WILLIAM C. WHITAORE, OF ST. LOUIS, MISSOURI, ASSIGNOR OF TWO-THIRDS TO JOHN F. BAUMGARTNER AND SHEPARD KNAPP, OF SAME PLACE.

AIR-PUMP.

SPECIFICATION formingpart of Letters Patent No. 508,495, dated November 14, 1893.

v Application filed March 29,1892. Serial No. 426,919. (No model.)

To all whom it may concern:

Beit known that I, WILLIAM G. VVHITACRE, a citizen of the United States, residing in the city of St. Louis and State of Missouri, have invented certain new and useful Improvements in Air-Pumps, of which the following is a full, clear, and exact description.

My invention relates to air pumps designed to compress air, especially to compress air to be used to operate pneumatic brakes in train service.

It has for its object the simplification of its construction as a whole, adapting it to be practically operative, at the same time as inex pensively constructed.

It consists in the hereinafter described improvements in such a device, in which the principal feature of novelty lies in a'form of construction adapting a simple slide valve to be used to control the How of the steam to the steam cylinder. 7

In the accompanying drawings, in which like numerals of reference denote like parts in the several figures, Figure 1 is a side elevation of my new pump. Fig. 2 is a vertical section taken on the line 2-2 in Fig. 1; and Figs. 3, 4., and 5 are cross-sections taken, respectively, on the lines 33, 44, and 55 in Fig. 2.

The pump consists in the steam cylinder 1 and the air cylinder 2, which are rigidly connected by the semi-circular rib portion 3. T0 the ends of the piston rod 4. are secured the steam piston head 5 and the air piston head 6, both of which are fitted in the usual manner, with steel packing rings, to their respective cylinders. To the side of the steam cylinder is secured the steam chest 7, which communicates with the interior of the steam cylinder, at either end of the same, by the ports 8 and 9 and with the external atmosphere by the exhaust port 11. Live steam is conducted to the steam chest 7 by the conduction pipe 12. The inflow of the live steam to the steam cylinder 1, from the steam chest 7, is controlled by the slide valve 16 which is connected to, and operated by, the valve rod 13, through the stirrup 20. To the projecting end of the valve rod 13, which is passed through the gland 44, is rigidly secured one end of the intermediate connecting rod 14;, the other end of which is adj ustably connected with the reciprocating rod 15. a The ends of the rod 15 are passed through, respectively, proper glands 21 and 22 into the interior of the air and steam cylinders, and extends to a convenient distance therein, adapting it to be operated, in the operation of the pump, in its reciprocations, as hereinafter described, by the steam and air pistons, 5 and 6, striking against the end thereof.

The air pump is a duplex pump, that is, operating to compress the air in its movement in either direction. The air cylinder is provided, for this purpose, with induction Valves inder and which are perforated at their exterior ,ends to permit the inflow of theair therethrough. In the valve 23, it being seated and closed bya vertically upward movement, there is placed beneath the same a compression spring 27,0ne end of which rests against a perforated plate 28, which is screwed in under the plug 25, and the other end against the lower end of the valve, the spring at all times tending to close the valve. The valve 24 is closed by gravity, it being inserted in the upper, open end of the plug 26, the cross-pin 29 preventing its withdrawal from the plug.

The normal position of the pump is vertical, as shown. The weight, therefore, of the pistons 5 and 6 and the connecting piston rod 4 will tend to help the steam in the downward movementof the same. This, however, can be'counterbalanced by the spring 27, which can be constructed of such a strength as to just balance the weight of the pistons and connecting rod, so that the steam will have the same operative effect in both directions. In either end, respectively, of the auxiliary air chamber 30, which is formed in the side of air cylinder casing, are secured the 5 valve plugs 31 and 32, in which are fitted the eduction valves 33 and 34. The valves 33 and 34: are similar in construction to the induction valves described. They are both placed and constructed as to bejgravity clos- IOO ing. Each plug is formed with a laterally extending duct 35 and 36, respectively, which,

when the plugs are in position, communicate, respectively, with the eduction ports 37 and 38, formed in the casing of the air cylinder, forminga communicating passage from either end of the air cylinder to the valve chambers, as illustrated in Fig. 2 and, for the valve 34, in Fig. 4.

The valve-plug 32 is formed closed on its inner end; that is, across the lower end of the valve-chamber for the valve 34, the laterallyextending duct communicating with the interior of the valve-chamber, only. In order, therefore, to aiford communication between the auxiliary air-chamber 30, and the valve chamber, the valve-plug 32 is formed with several longitudinal passages 39. (See Figs. 2 and 4.)

The longitudinal movement of the valve 34 is limited by the closing screw cap 40, and the cross rod 41 efiects the same purpose in the valve 33.

Into the side of the casing of the auxiliary air chamber 30 is secured the end of the pipe 42 which connects the pump with the air reservoir.

The principles of operation of my improved pump are as follows: In Fig. 2 the relative position of the coacting parts indicated are what they would assume just at the final part of the downward stroke of the piston rod 4, as indicated by the arrow 43; that is, the valveoperating rod has just been struck by the piston 5, and this has moved the slide-valve 16 to begin connecting the port duct 8 of the steam cylinder with exhaust port 10, which has, up to this part of the stroke, been in communication with the live steam, only, and to begin connecting the eduction port 9 with the live steam, and, in the air cylinder, the air aheadbelow as indicated in the drawingsis being compressed and forced through valve 33 into the conduction pipe 42, as indicated by the small arrows at valve 33. At the same time, the pressure back of the valve 34, through the ducts 39 closes the same, and air is being drawn into the upper end of the air cylinder through inlet valve 23, preparatory to its being compressed on the return stroke of the piston head 6. Before, however, the piston has fully completed its stroke in this direction, the valve operating rod 15 has been moved sufficiently to operate the slide-valve 16 to fully uncover the port 8 to the exhaust port 10, and the port 9 to the live steam, whereby the pressure of the live steam is acting on the under side of the piston 5, only. The piston head 5 will thus be forced upward, and the air in the upper end of the air cylinder be compressed and forced through the outlet valve 34, and the lower end be filled through the inlet valve 24. Before the end of the stroke of the piston heads in this direction, z'. e., upward, the head 6 has struck against the rod 15 and thrown the slide valve 16 to direct the live steam to the upper end of the steam cylinder, when the operation described will be repeated.

The simplicityof construction and consequent operation are at once evident features of ad vantage, as are, also, the consequent accessibility of all the valves of the air compressing cylinder.

In an air pump, the combination with a steam and an air cylinder in vertical alignment, of a double headed piston rod operating in andbetween said cylinders, a cut off for the steam cylinder, a rod adapted to control the cut off, said rod receiving its motion from the alternating contact of the two piston heads, inlet ports in each end of the air cylinder, the upper of which is controlled by a spring seated valve, and exhaust ports at the sides of the air cylinder and near each end thereof, said ports being controlled by gravitating valves, substantially as described.

In testimony whereof I have affixed my signature, in presence of two witnesses, this 19th day of March, 1892.

WILLIAM C. WHITACRE.

Witnesses:

SHEPARD KNAPP, H. K. WAGNER. 

